Since a portable electronic device such as a personal digital assistant (PDA) usually comes with a touch screen to let users enter text and graphics, or select a software option of the electronic device on the touch screen by using a pen. Thus, the pen is used as a mouse.
In general, PDA manufacturers adopt a special material to make such pen in order to protect the screen better. Therefore, any input via the screen is limited to a particular pen only. If a user uses another pen for the input, it will damage the screen (such as a scrape on the surface). Sin the pen is used very often, it is easy to forget to put the pen back into the pen holding slot, and thus the user may lose the pen very easily, and it also creates a problem of being unable to input data or instructions without the pen to the user. The way of solving the problem of easily losing the pen and designing a structure for preventing the loss of the pen are urgent subjects for the electronic industry.